And we begin with mounting concern over security at the olympics in sochi, now just a little more than two weeks away. Tonight, that new video and on it, an ominous threat from a team that has struck already. At least one American senator tonight saying it's too dangerous to go to sochi. ABC's chief investigative correspondent Brian Ross on the new terror threat tonight. Reporter: Amid growing concerns about security, the terror group behind the last two suicide attacks in Russia today posted this video online purporting to show the two men responsible. They were shown allegedly building bombs and heading to their targets. The men said their group had more attacks planned, a surprise package, they called it, and one especially, they said, for tourists who will come to the olympics. In a separate online statement, the terror group said the volgograd attacks are only the beginning, and said future tlement threats could go as far as to include chemical attacks. The long and the short of it is, I think Putin and the Russian government will be very lucky if they are able to get through the olympics without an incident. Reporter: Today, one U.S. Senator said it was too dangerous to attend the olympics in sochi. I would not go. And I don't think I would send my family. Reporter: But Russian authorities insist they have security issues in hand. They released their own video today, showing a full scale assault on a suspected militant stronghold in Daigle dagestan. Seven people were killed, according to Russian officials, who say their iron fisted take no prisoners approach will make the olympics safe. Wow, just a couple of weeks away. Brian with us now. The first real test of the security comes tomorrow? Reporter: That's right. The olympic torch relay goes through volgograd where the two suicide attacks have already taken place. Security will be in a lockdown situation in that city. A real test of the ability to withstand terror threats. Brian Ross on a Sunday night. Thank you.

This transcript has been automatically generated and may not be 100% accurate.